You develop a style over time, but I think you should always be trying new things to keep it fresh. It shouldn't become stale or expected, and experimenting helps, even if you never publish or show anyone your experiments.

I don't like the term "writer's block." I feel like it gives too much power to the idea. Fear of the name only increases fear of the thing itself, according to some smart witch/wizard or another. (Harry Potter references ftw.)

My friend Ian talks about "refilling the well," which I think fits much better. Think of the well as potential for creativity. You've got lots of passion for a story, lots of ideas and all that fancy jazz. The well is full. Then you're 50,000 words into a novel and running on empty. Your well needs refilling. This will happen differently for each writer: some need to read their favorite book for the billionth time; others need to people watch; some need to watch their favorite television show or movie and think about its character arcs or themes; others need to write something shorter--poetry, maybe, or just some freewrite scribbles; others still need to get away from writing for a while, maybe by drawing or knitting or getting lost on Tumblr for a few hours. Take the time to do this so you don't run yourself into the ground. When you've refilled your creativity well, you can return to your project or start a new one, as the case may be, with a renewed zest for your craft.